...I'm not sure how I feel about semicolons.
George Orwell once wrote a letter to a friend where he said that in his new novel, he was proud of the fact that he hadn't used a single semicolon, because he'd decided it was a "completely useless" piece of punctuation. (IIRC the novel was "Coming Up for Air".) Funny thing is, though, there *are* some semicolons in "1984" (which was his last book). Did he change his mind, or just forget about his rule? (He was pretty sick when he wrote 1984 so it could have been the latter).
Also, as TFS points out, Vonnegut said "don't use semicolons" but he *did* use them here and there.
One thing is for sure-- semicolons can be sort of a crutch for lazy or bad writers. To borrow a phrase from Orwell, they can prevent a lot of sentences from "coming down with a bump". In college I had to read a lot of Henry James and I remember thinking that he was addicted to semicolons. I started to mentally substitute a period whenever there was a semicolon, and I noticed that when you did that, his prose sounded flat and clumsy.
Semicolons can also be very, very pretentious if you use them wrong. Here's an example, from a crappy article about olives that I read many years ago: "Bottled olives are acceptable; canned are not". Kind of vomit-inducing, isn't it? (It's funny how examples of bad writing stick in your head).